1)    It is forbidden to derive active benefit from anything belonging to someone else without his knowledge. This is true even in the case that he is absolutely certain that when the owner finds out about it he will be very happy because he likes him so much, that it is nevertheless forbidden. (Kitzur Shulchan Aruch 182)

2)    It follows that it is forbidden to enter the garden of one’s friend and take fruit without the knowledge of the owner even though he is a friend and beloved companion of the owner of the garden and he will definitely be happy that his friend is eating his fruit, nevertheless since at this moment in time he does not know about it, he is deriving benefit in a forbidden manner. Many people slip up in this because of their lack of knowledge about this matter. (ibid)